Thanks Paul.

Based on the above discussion, I guess we need to change the the existing Stratos messaging model to support the Pub/Sub model and MQTT protocol.AFAIU following areas we need to modify in the Stratos messaging model.

Step 1 :
We need to remove the header based message distinguished.
AFAIU there will be major changes have to be done for the "org.apache.stratos.messaging" component. 
Also we need to change the cloud controller, load balancer and cartridge agent accordingly.Also AFAIU Load balancer->CEP->autoscaler message transition will not be affected by this as there are no message distinguish based on the headers AFAIK. Please correct me if I am wrong here.

Step 2 :
Need to reorganized our structure of events schema.(To support topic hierarchy as Paul suggested)
AFAIU currently we don't have such hierarchical structure in our schema.So we need to reorganized and normalized schema further to support the schema hierarchy. WDYT?

Further , I have done some code level testing with the MQTT protocol in both java and python with the topic hierarchy.Pleas find the code samples from here.
https://github.com/gayangunarathne/MQTT-Pub-Sub

But to integrate this with the current messaging setup ,I think we need to carry above two steps first.

Please share your thoughts on this.


Thanks,
Gayan




On Tue, Sep 2, 2014 at 4:16 PM, Paul Fremantle <paul@wso2.com> wrote:
Gayan

Normally you would structure your topic hierarchy to be capture the structure of events and the schema

e.g. 
topic
/metrics/datacentre1/system1/cpu
message
{ json format for cpu data }

Paul


On 2 September 2014 11:40, Gayan Gunarathne <gayang@wso2.com> wrote:
Hi Paul,

AFAIU with the existing message design and with your points with the Pub/Sub ,+1 for improve our Startos messaging model as far as we can as it will improve the performance as well as standards.As far as I understood the current messaging model , we can thinking about following two suggestions.

Suggestion 1 - 
We can used separate topic for the every event type.But AFAIN there are around 30 events(same schema or shape) around in the current scenario and I supposed it is growing as well.Please correct me if I am wrong here.So we have to maintain separate topics for the each events and then easily we can distinguished the messages based on the topic.

Suggestion 2 -
With the current implementation we used the "event-class-name" value to distinguished the messages.IMO also We don't need to distinguished the messages based on the header and we can easily include that in the message body.But still I guess there will be a overhead is that every time we need to deserialize  the JSON message and see what is the message class name is.WDYT?

Please share your thoughts on this and also it is really appreciate if you can recommend any other suggestion in your mind to improve the current messaging model.


Thanks,
Gayan



On Tue, Sep 2, 2014 at 2:24 PM, Paul Fremantle <paul@wso2.com> wrote:
Gayan

I don't understand this. I think this is a mistake on how to use Pub/Sub. 

The headers timestamp and expiry should probably be in the message (not sure)
The destination is part of the pub/sub network
The event-class should be implicitly based on the topic. In other words in a pub/sub network, every message in a specific topic should have the same schema or shape. You shouldn't need some extra header to know which schema it is.

Paul



On 2 September 2014 09:44, Gayan Gunarathne <gayang@wso2.com> wrote:
Hi Paul,

Please find the example of existing message header and body.AFAIK "event-class-name" is the header value used for distinguish the messages.

header: key expires , value 0
header: key timestamp , value 1409646637558
header: key destination , value /topic/topology
header: key persistent , value true
header: key priority , value 4
header: key event-class-name , value org.apache.stratos.messaging.event.topology.CompleteTopologyEvent

Message body:

 {"topology":{"serviceMap":{"gateway":{"serviceName":"gateway","serviceType":"SingleTenant","clusterIdClusterMap":{"gatewaygateway.am.wso2.com.dom":{"serviceName":"gateway","clusterId":"gatewaygateway.am.wso2.com.dom","autoscalePolicyName":"auto-scl-pol1","deploymentPolicyName":" dep-pol1","hostNames":["foo.org"],"tenantRange":"1-*","isLbCluster":false,"memberMap":{"gatewaygateway.am.wso2.com.dom-member-2":{"serviceName":"gateway","clusterId":"gatewaygateway.am.wso2.com.dom","networkPartitionId":"network-partition1","partitionId":"cloud-partition1","memberId":"gatewaygateway.am.wso2.com.dom-member-2","portMap":{"9080":{"protocol":"http","value":8080,"proxy":9080}},"memberPublicIp":"127.0.0.1 public","status":"Activated","memberIp":"127.0.0.1 private","properties":{"mykey1xxxxxxxxx":"myvalweccccccccccccccc"}},"gatewaygateway.am.wso2.com.dom-member-1":{"serviceName":"gateway","clusterId":"gatewaygateway.am.wso2.com.dom","networkPartitionId":"network-partition1","partitionId":"cloud-partition1","memberId":"gatewaygateway.am.wso2.com.dom-member-1","portMap":{"9080":{"protocol":"http","value":8080,"proxy":9080}},"memberPublicIp":"127.0.0.1 public","status":"Activated","memberIp":"127.0.0.1 private","properties":{"mykey1xxxxxxxxx":"myvalweccccccccccccccc"}},"gatewaygateway.am.wso2.com.dom5863cf8d-2746-4be1-91e9-da98c2bcb5a9":{"serviceName":"gateway","clusterId":"gatewaygateway.am.wso2.com.dom","networkPartitionId":"network-partition1","partitionId":"cloud-partition1","memberId":"gatewaygateway.am.wso2.com.dom5863cf8d-2746-4be1-91e9-da98c2bcb5a9","portMap":{},"memberPublicIp":"public IP","memberIp":"private IP"},"lb-member-id-1":{"serviceName":"lb","clusterId":"lbisuruh.lk.domain","networkPartitionId":"network-partition1","partitionId":"cloud-partition1","memberId":"lb-member-id-1","portMap":{},"memberPublicIp":"public IP of apistore","memberIp":"private IP of apistore"}},"properties":{"mykey1weeee":"myvalweeeeeeeee1","mykey1tttttttt":"myvalweetttttttttttt1"}}},"portMap":{"9080":{"protocol":"http","value":8080,"proxy":9080}},"properties":{"mykey1weeee":"myvalweeeeeeeee1","mykey1tttttttt":"myvalweetttttttttttt1"}},"apistore":{"serviceName":"apistore","serviceType":"SingleTenant","clusterIdClusterMap":{"apistorestore.am.wso2.com.doma":{"serviceName":"apistore","clusterId":"apistorestore.am.wso2.com.doma","autoscalePolicyName":"auto-scl-pol1","deploymentPolicyName":" dep-pol1","hostNames":["foo.org"],"tenantRange":"1-*","isLbCluster":false,"memberMap":{"apistorestore.am.wso2.com.doma298e2959-a3b4-45a0-a11f-7671606158ed":{"serviceName":"apistore","clusterId":"apistorestore.am.wso2.com.doma","networkPartitionId":"network-partition1","partitionId":"cloud-partition1","memberId":"apistorestore.am.wso2.com.doma298e2959-a3b4-45a0-a11f-7671606158ed","portMap":{},"memberPublicIp":"pub ip","status":"Activated","memberIp":"ip","lbClusterId":"lbmongolb594224131.mongolb.dom"}}}},"portMap":{"9080":{"protocol":"http","value":8080,"proxy":9080}}},"lb":{"serviceName":"lb","serviceType":"SingleTenant","clusterIdClusterMap":{"lbisuruh.lk.domain":{"serviceName":"lb","clusterId":"lbisuruh.lk.domain","autoscalePolicyName":"auto-scl-pol1","deploymentPolicyName":" dep-pol1","hostNames":["foo.org"],"tenantRange":"1-*","isLbCluster":false,"memberMap":{}}},"portMap":{"9080":{"protocol":"http","value":8080,"proxy":9080}}}},"initialized":false}}


Thanks,
Gayan



On Tue, Sep 2, 2014 at 1:49 PM, Paul Fremantle <paul@wso2.com> wrote:
Can you post an example of the headers and body?

Paul


On 2 September 2014 09:17, Gayan Gunarathne <gayang@wso2.com> wrote:
Hi Paul,

Currently we have existing java based message publisher with the headers. Here we try to use those published messages with the python client. If we use JSON structured message with  headers enclosed we have to change all other current implementations as well. AFAIK We will distinguished the messages with their header value.So my point is if we used this sort of JSON structure for messages, we need to change all the current messaging model.

OTOH with the Stomp protocol with python client we were able to get those header values and used those messages as it is. 

Thanks,
Gayan


On Tue, Sep 2, 2014 at 1:04 PM, Paul Fremantle <paul@wso2.com> wrote:
What headers do you need to pass?

The way of doing headers with MQTT is to use a structured message (e.g. JSON) and put some headers into the JSON.

Paul


On 2 September 2014 07:58, Gayan Gunarathne <gayang@wso2.com> wrote:

We did some analysis regarding the MQTT protocol as well.Following are our findings regarding the MQTT.

MQTT is low bandwidth consumption messaging protocol which supports pub/sub protocol with the following limitations. 
  • It has fixed header (2 bytes) . Specifications mentioning that it can be extended.But AFAIU clients[1] didn't support for this header extension. We have checked the MQTT with the messages published with headers and we didn't receive the header on those.Only receive the message body.
  • The payload size for a MQTT message is 256MB.I guess design point for MQTT usage is targeted at more constrained devices.[3]. MQTT is better at a high volume of low size messages.
  • It is supports only topic.This will not be a issue currently in our scenario as we used only topic currently AFAIK.[4]

I guess it build with above limitations and it is very good choice for the mobile and small application as it is very lightweight and low power.[5] WDYT?

Please share your thoughts on this.

[3] http://stephendnicholas.com/archives/1217


On Mon, Sep 1, 2014 at 4:32 PM, Gayan Gunarathne <gayang@wso2.com> wrote:
Thanks Paul.

We will check on this paho-mgtt python library as well.

Thanks,
Gayan




On Mon, Sep 1, 2014 at 4:17 PM, Paul Fremantle <paul@wso2.com> wrote:
Python has excellent pure python MQTT support. 

pip install paho-mqtt


Paul


On 1 September 2014 11:40, Gayan Gunarathne <gayang@wso2.com> wrote:
Hi Paul,

Here we try to connect the our existing Apache ActiveMQ with the pure python.(We try to replace our java cartridge agent with the python as after that we can remove the java dependency from the cartridge itself). 
In the initial research we didn't notice such a pure python libraries with the MQTT  which can connect with the ActiveMQ. Also with the initial reading I guess they are recommend it for the mobile applications as its low bandwidth consumption.Also I am noticed lot of web socket based applications are developed through MQTT.

Thanks,
Gayan


On Mon, Sep 1, 2014 at 3:42 PM, Paul Fremantle <paul@wso2.com> wrote:

Have you looked at mqtt?

Paul

On 1 Sep 2014 12:10, "Gayan Gunarathne" <gayang@wso2.com> wrote:

Hi All,

As per our initial research on the python based messaging implementation of python cartridge agent and discussion[1] we can summarize our findings as following.

1.AMQP

Apache ActiveMQ used the AMQP 1.0 protocol. We found C based client library (proton) [2] which can be used with python.
But it is a platform dependent library and every time we need to install the libraries based on the architecture and OS version.IMO this will be difficult us to manage as we need to install the libraries based on the platform.

Other python libraries(txAMQP ,pika etc) supports AMQP 0.9 which fails to connect with the ActiveMQ.


2.STOMP

We can connect to the ActiveMQ with the STOMP protocol by using the STOMP python client library[3].IMO we can used STOMP with ActiveMQ without worry about the platform based library installation.By considering our scope of the cartridge agent I think it is better to have a platform independence cartridge as far as we can. Then, IMO STOMP based messaging queue implementation  will be more manageable when we increase our number of platform supported.
WDYT?

When comparing the performance of theses two protocols it looks like there are no such huge difference[4].I guess the performance also tightly coupled with the message broker you are using as well.OTOH Apache ActiveMQ recommended way also to used the STOMP with the python[5].


Please share your thoughts on this.

[1] Stratos Python Cartridge Agent


Thanks,
Gayan



--


Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Paul Fremantle
CTO and Co-Founder, WSO2
OASIS WS-RX TC Co-chair, Apache Member

UK: +44 207 096 0336

blog: http://pzf.fremantle.org
twitter.com/pzfreo
paul@wso2.com

wso2.com Lean Enterprise Middleware

Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.



--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Paul Fremantle
CTO and Co-Founder, WSO2
OASIS WS-RX TC Co-chair, Apache Member

UK: +44 207 096 0336

blog: http://pzf.fremantle.org
twitter.com/pzfreo
paul@wso2.com

wso2.com Lean Enterprise Middleware

Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.



--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Paul Fremantle
CTO and Co-Founder, WSO2
OASIS WS-RX TC Co-chair, Apache Member

UK: +44 207 096 0336

blog: http://pzf.fremantle.org
twitter.com/pzfreo
paul@wso2.com

wso2.com Lean Enterprise Middleware

Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.



--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Paul Fremantle
CTO and Co-Founder, WSO2
OASIS WS-RX TC Co-chair, Apache Member

UK: +44 207 096 0336

blog: http://pzf.fremantle.org
twitter.com/pzfreo
paul@wso2.com

wso2.com Lean Enterprise Middleware

Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.



--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985
 




--
Paul Fremantle
CTO and Co-Founder, WSO2
OASIS WS-RX TC Co-chair, Apache Member

UK: +44 207 096 0336

blog: http://pzf.fremantle.org
twitter.com/pzfreo
paul@wso2.com

wso2.com Lean Enterprise Middleware

Disclaimer: This communication may contain privileged or other confidential information and is intended exclusively for the addressee/s. If you are not the intended recipient/s, or believe that you may have received this communication in error, please reply to the sender indicating that fact and delete the copy you received and in addition, you should not print, copy, retransmit, disseminate, or otherwise use the information contained in this communication. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.



--
Best Regards,

Gayan Gunarathne
Technical Lead
WSO2 Inc. (http://wso2.com)
email  : gayang@wso2.com  | mobile : +94 766819985